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No single factor is behind the decline in honey bee health, Marla Spivak, a leading researcher in bee health said recently. Instead, she said the “four P’s” – parasites, pathogens, pesticides and poor nutrition – combine to compromise bee health or, in some cases, kill bees. Bee expert Lynn Williams: “The Varroa mite, they call them the destructors, showed up in the United States in 1981. It came out of Southeast Asia and spread worldwide.” Not only do the mites get into the bee larvae and eat all of the queen’s eggs, but Varroa mites spread viruses from hive to hive, pesticides can alter bee behavior in significant ways, and a lack of floral resources can leave bees less able to fight off the effects of the other stressors.

Spivak said beekeepers began “screaming bloody murder” in 2006 when they started losing colonies in large numbers,, and while the latest colony survey by the Bee Informed Partnership showed annual losses of 33 percent, the second-lowest rate in seven years, that number is still well above what beekeepers consider acceptable.

The varroa mite, which Spivak called “a very obnoxious parasite,” feeds on the bees, reducing their body weight, including necessary proteins and carbohydrates. But “the most insidious thing about this pest,” she said, is that as it feeds on the bee, it picks up other viruses that were not causing problems and then transfers them to other bees.

Spivak said that when colony losses accelerated about 10 years ago, beekeepers “reluctantly” began treating their hives with miticides. Those who do not treat can increase the chances that colonies belonging to nearby beekeepers will become infected. But treatment can bring its own problems, Spivak said – residue in the wax comb and “secondary effects” on bee health.